Electric toothbrushes are well known and have been on the market for years. With typical electric brushes all of the tufts of bristles on the brush head are vertically oriented relative to the top surface of the head. The tufts are oscillated, rotated and/or translated in order to provide enhanced tooth cleaning capability.
German Gebrauchsmuster 8807968.6 discloses a head for an electric toothbrush. A first group of circular tufts 18 are arrayed in a first ring about the center of rotation of the head. A second group of taller circular tufts 16 are arrayed in a second ring which is outside the first ring and also encircles the center of rotation of the head. All of tufts 16 and 18 are circular in cross-section and are canted away from the center of the head at an acute angle relative to a top surface of the head
A problem with this brush is that all of the tufts have a circular cross-section. Such tufts are not that effective at penetrating between teeth to clean the interdental or approximal areas of the teeth. Further, all but one of the tufts are angled away from the center. Such a tuft pattern tends to flair (flatten) out even more than designed during use, thereby having the same brushing characteristics as a worn-out standard brush. Additionally, none of the tufts are angled along the direction of the rotational circumference which results in even poorer interdental penetration of the bristles.
European Patent 0765642 also discloses a head for an electric toothbrush. There are a number of bristle tufts 17 which are vertically oriented on the head. Bristle tufts 13, 15 are located about a perimeter of the circular head and are tilted at an acute angle along a circumference of a top surface of the head. All of the tufts on the head have a circular cross-section.
Again we see the problem of a brush head in which all of the tufts have a circular-cross-section: such tufts do not penetrate well in the approximal tooth areas. This head also has no tufts which are angled away from the center to sweep along the gum line or gingival margin of the mouth. Further, in two pairs of the tufts 13, the tufts are adjacent to each other and are angled towards each other. These two tufts appear to be in contact. A downside to this tuft arrangement is that the two adjacent tufts can tend to interfere with each other during use of the brush. In addition, due to the tuft configuration and shape, a lot of the available space of the head is not used. This reduces efficacy and increases wear of the head (flare) upon use. For effective brushing approximately 32-36% of the head surface must be covered with tufts/bristles.